In a variety of consumer packaging applications, it is important to supply paperboard or corrugated cardboard cartons which are capable of being conveniently, yet securely, opened and reclosed repeatedly. The ability to be repeatedly opened and closed down in a lockable manner is particularly important where the carton is used for storage of granular or powdered material, such as laundry detergent powder. Various approaches have been undertaken to address the repeated opening and closing requirements by means of carton designs using different types of interlocking flaps.
An exemplary reclosable carton design is disclosed in U.S. Pat. No. 5,161,734 to Ruehl ("Ruehl"). Ruehl proposes a flip-top reclosable carton which employs an integral tear strip as means by which a user may strip open the carton. Removing the tear strip delineates the carton into a lid and a base, where the lid is hingedly connected to a back wall of the base. After the tear strip is removed, the carton is opened by lifting the lid up. Subsequently, the carton is reclosed by pushing the lid back down to its original position. Repeated closing and positive locking of the carton is realized by means of snap engagement of a distal attachment portion on the lid and a proximal locking portion on the base.
In another carton design, locking of the lid and base is realized by a friction fit between the lid and a corresponding engaging portion of the carton base.
Paperboard or corrugated cardboard cartons are typically formed from rolls of board which are cut into "blanks." Score lines are scribed between sections of a blank to divide the blank into rectangular sections and to facilitate folding of these sections with respect to one another. In forming a carton from the blank, a top, side, or bottom panel of the carton is initially left unsealed so that the cannon may be filled with a product through the unsealed panel. Once the carton is filled with the product, the carton is sealed and the filled carton is ready to be sold to a consumer.
The flip-top reclosable carton disclosed in U.S. Pat. No. 5,161,734 to Ruehl is a side-filled cannon which is filled with a product through an unsealed side wall. The unsealed side wall of such a carton is subsequently sealed using a non-conventional folding sequence requiring specially-engineered form-fill-seal equipment. The side wall of the carton in Ruehl, for example, is created from top and bottom minor flaps, a back major flap, and a pair of overlapping front major flaps. One of the front major flaps is associated with a front inner panel, while the other of the front major flaps is associated with a front outer panel. In one version, the foregoing flaps are folded inward by 90 degrees in the following sequence: bottom minor flap, back major flap, pair of overlapping front major flaps, and top minor flap. The design of the carton in Ruehl dictates the use of this non-conventional flap folding sequence. Like the carton in Ruehl, side-filled cartons using a friction-fit closure have historically been sealed using a non-conventional flap folding sequence due to the design of the various flaps used to form the side walls of these cartons.
A need therefore exists for a side-filled, flip-top reclosable carton which can be sealed using a conventional flap folding sequence so that the carton is entirely compatible with conventional form-fill-seal equipment.